Airliners or military also?
I want to leap in here with the last 'potentially' airworthy Comet based at Bruntingthorpe....... but that's been with the MOD all it's life so not sure if it counts as an airliner. First flew 26/09/63
Failing that, I guess it would have to be one of those 707's still operating round Africa or Iran. Unless one of the old Soviet block countries still have a Tu104 airworthy.